A photosensitive paste has recently widely been used to form a fine pattern on a substrate with photolithography.
A negative photoresist containing (a) a photopolymerization initiator, (b) an acryl monomer, and (c) a main polymer (such as an acryl polymer) has been proposed as one of photosensitive pastes used in such photolithography (see paragraph 0029 of Japanese Patent Laying-Open No. 2010-224569 and the like).
In order to form a fine pattern on a substrate, application of photolithography with the use of a negative photoresist is effective as in Japanese Patent Laying-Open No. 2010-224569. In addition, a negative photoresist in which inorganic powders have been dispersed can also be used.
Then, by using such a photosensitive paste containing inorganic powders, applying photolithography, and performing a firing treatment, a fine inorganic pattern (such as a conductor pattern or an insulator pattern) can efficiently be formed on a substrate.
As described above, however, a photocured product of the negative photoresist in Japanese Patent Laying-Open No. 2010-224569 containing (a) a photopolymerization initiator, (b) an acryl monomer, and (c) a main polymer (such as an acryl polymer) is less likely to thermally be decomposed in heat treatment in a non-oxygen atmosphere.
Therefore, for example, in a case that an electrode is made of a base metal for the purpose of prevention of migration or the like and a paste pattern formed of the photosensitive paste above is subjected to firing treatment in the non-oxygen atmosphere, a residue of carbon (remaining carbon) derived from the photocured product may be generated.
Then, for example, in a case that an insulating layer is to be formed of a photosensitive paste in which glass powders as inorganic powders have been dispersed, insulation reliability becomes poor due to sintering interfered by the residue of carbon.
In addition, in a case that a conductor pattern (an electrode) is to be formed of a photosensitive paste in which copper powders as inorganic powders have been dispersed, conduction becomes poor due to sintering interfered with by the residue of carbon.